Whats the big deal with LS7 lifters?
#1
TECH Apprentice
Thread Starter
iTrader: (5)
Join Date: Nov 2004
Location: Metro Detroit
Posts: 309
Likes: 0
Received 0 Likes
on
0 Posts
Whats the big deal with LS7 lifters?
I have seen some threads saying how terrible they are. Is this just because they are not linked and can rotate in the bore? Or is there issues with them failing?
#2
TECH Resident
iTrader: (4)
the lifter often gets blame for failing when its improper component matching elsewhere in the valvetrain that often causes it. the lifter has a pretty hard job to do, so to blame everything on "bad lifters" isn't telling the whole story.
that being said, lots of guys that have failures seem to have run them in applications with high spring pressures and aggressive lobe profiles with high lifts....things they were not designed to handle. couple that with improper push rod size and you've got several factors all working together to collapse the lifter. they seem to work for a lot of people when the valvetrain is set up properly but I wouldn't use them on anything more than a very mild setup.
that being said, lots of guys that have failures seem to have run them in applications with high spring pressures and aggressive lobe profiles with high lifts....things they were not designed to handle. couple that with improper push rod size and you've got several factors all working together to collapse the lifter. they seem to work for a lot of people when the valvetrain is set up properly but I wouldn't use them on anything more than a very mild setup.
#3
TECH Apprentice
Thread Starter
iTrader: (5)
Join Date: Nov 2004
Location: Metro Detroit
Posts: 309
Likes: 0
Received 0 Likes
on
0 Posts
I guess I should consider running a link bar. My set up isn't exactly mild and I will be running Brian Tooley .660 springs. I see morel has a good reputation but also heard they are tough to get a hold of.
#6
11 Second Club
iTrader: (1)
The biggest "issue" with the LS7s is that most people are stupid and pretend they are some massive upgrade when they are simply another OEM lifter. The failure rate on them seems to be a little higher than older stuff but that could certainly be due to aggressive lobes and poor setup. Really though it is not like they are junk or anything, just a cheap OEM replacement.
Trending Topics
#8
TECH Senior Member
iTrader: (35)
The biggest "issue" with the LS7s is that most people are stupid and pretend they are some massive upgrade when they are simply another OEM lifter. The failure rate on them seems to be a little higher than older stuff but that could certainly be due to aggressive lobes and poor setup. Really though it is not like they are junk or anything, just a cheap OEM replacement.
The following users liked this post:
MYALIMONY (05-28-2022)
#10
TECH Apprentice
iTrader: (1)
Join Date: Mar 2009
Location: LA
Posts: 356
Likes: 0
Received 0 Likes
on
0 Posts
I'm using LS7 lifters, in my 383, with .619 lift cam, and rev limiter set to 7200, no issues at all, and misc info, my power drops off at 6500 only see 7200rpm at the end of a quarter mile pass in fourth gear, have 4.08 gears
#12
Super Hulk Smash
iTrader: (7)
I don't think anyone is saying the LS7 lifters are terrible. Many people run them without problems. The issue is the entire valvetrain.
When you run heavy valves, high spring rates, and fast ramp cams, you put a lot of stress on an OEM spec component. Can it survive? Sure. If you're setup is well optimized and setup correctly, the lifters will probably be ok. But merely ok.
And optimized means: milder endurance lobes, less spring pressure, and lighter valves combined with light and strong rockers and very strong pushrods.
What do I see most of the time? XE-R or LSK lobes, big stainless, heavy valves, and huge spring pressure to control those lobes with heavy valves. Then I see 5/16th pushrods and heavy aftermarket roller rockers. And after 10k miles the lifter fails or turns in the bore and takes out an engine. Sorry, I don't care if you are running them successfully or not. It's on borrowed time if you're not running a truly optimized setup that doesn't "loft" the lifter.
When you run heavy valves, high spring rates, and fast ramp cams, you put a lot of stress on an OEM spec component. Can it survive? Sure. If you're setup is well optimized and setup correctly, the lifters will probably be ok. But merely ok.
And optimized means: milder endurance lobes, less spring pressure, and lighter valves combined with light and strong rockers and very strong pushrods.
What do I see most of the time? XE-R or LSK lobes, big stainless, heavy valves, and huge spring pressure to control those lobes with heavy valves. Then I see 5/16th pushrods and heavy aftermarket roller rockers. And after 10k miles the lifter fails or turns in the bore and takes out an engine. Sorry, I don't care if you are running them successfully or not. It's on borrowed time if you're not running a truly optimized setup that doesn't "loft" the lifter.
#17
TECH Resident
iTrader: (4)
Brian's response on page 3.
My takeaways from it....the SLR's aren't anything much different from the LS7's except that they are valved for a slower leakdown rate. This helps you at lower rpm when the lifter will typically leak down too quickly since the oil pressure isn't sufficient to the point that it can prevent net lift losses. So noise levels and lower end power losses are reduced.
However it still doesn't help with higher rpm valve float....if your valvetrain is still out of control to the point that you're lofting the lifter, I'd imagine these would float valves worse than stock since they have tighter tolerances (oil can't escape as fast) and they have the same preload / travel range as the stock lifter. It's just as important to have the valvetrain under control with these as it is with stock lifters and as it is with ls7's as it is with morel's and lunati's etc etc.
There is no "magic lifter", you have to assess the entire valvetrain